1. Field of the Invention
The present invention relates to a safety connector for household table-top electrical appliances, to be precise of the type constituted by an ensemble formed by two parts, one of which is fixed and constitutes a socket member mounted in the appliance, and the other is removable, constitutes an appliance coupler member mating with said socket member, and forms a terminal for an end of a flexible power cord that has at the other end thereof a plug member which may be plugged into an electric mains socket member, there being provided magnetic means allowing a stable mechanical and electrical connection of both parts to be maintained under preset conditions of normal use of the appliance and the mechanical and electrical disconnection of said two parts under an abnormal strain exerted on the appliance coupler member of the ensemble.
2. Prior Art
Safety connectors of the aforementioned type are known wherein the magnetic means, formed by the magnet and the active armatures, are located, in some cases, in the socket member of the household electrical appliance and, in other cases, in the removable part which, as a plug member, is electrically associated with the flexible power cord which is conventionally connected at the other end thereof to a mains socket, the passive armature being located in the other member.
As disclosure of the connectors of the first type, there can be cited the Japanese patent 62-60244, which discloses a female plug socket having an active magnetic arrangement and resilient contacts.
With regard to the connectors of the second type, there can be cited Japanese patent 50-54932 which discloses a female plug member having two differentiated connection stages, Japanese patent 52-05811 which discloses two paths of the power cord, and Japanese patent 62-03914 which discloses an arrangement to protect the magnetic means included in a female plug member from blows caused by accidental falls.
On the other hand, Japanese patent 10-041011 discloses a cord connector that consists of a male plug member having the active magnetic arrangement and which mates with a female plug member that includes the passive magnetic arrangement, constituting a connector for two cords, in which both parts are removable.
In the connectors of the first type, it is observed that they are fixed female type socket members including the active magnetic arrangement, while the connectors of the second type consist of removable female type plug members that include the active magnetic arrangement.
In both the above cases the connectors individually have the following drawbacks: a) the female socket members require that the removable plug members should be provided with connection pins that, projecting out from the insulating body member of the plug member, are susceptible of producing electric discharges or short circuits and of being deformed by blows occurring when accidentally dropped; and b) when the removable plug members are of the female type, they are excessively voluminous and heavy and are susceptible of being damaged if accidentally dropped.
With the purpose of avoiding such drawbacks the solution has been adopted of structuring a safety connector formed by two parts, a fixed one mounted in the household electrical appliance or similar appliance to be fed electrically and another removable one, removably associated with an electrical outlet, in such a way that the fixed part constitutes a male socket member including the active magnetic arrangement, while the removable part constitutes a female plug member including the passive magnetic arrangement.
According to the foregoing solution, the safety connector of the invention has been developed, which is characterized in that a socket member fixed to the appliance comprises pins, related with the electrical load bearing members of the appliance (heating elements, motors, etc.), and a grounding arrangement, between which there is a magnet arrangement and two active armatures therefor, while a removable plug member, complementary to the fixed socket member, comprises two resiliently flexible electrical contacts spatially mating with the pins of said fixed socket member, and between which there is located an iron plate member as passive armature which, in the positioning and plugging-in operations, is in facing alignment with the active armatures of the magnet and in contact with the grounding arrangement disposed in said socket member.
It is a feature of the invention that the socket member is constituted by a insulating capsular body member fixedly mounted in the appliance, from the bottom of which, there extend the pins and the grounding arrangement disposed against a wall and the magnet and the two active armatures thereof slightly project. It has a hollow section which, being complementary to the solid section of the body member of the removable plug member, is arranged with the open end thereof directed toward the outside of the appliance.
On the other hand, a further feature of the invention is that the removable plug member is constituted by an insulating body member that comprises in the interior thereof the wires of one end of the power cord connected to a fixed point of each one of the resiliently flexible electrical contacts housed in said body member, which are located inside respective passages that debouch in respective openings spatially mating with the pins of the socket member and flank the passive armature iron plate member facing the active armatures of the magnet of said socket member.
Another feature of the invention consists of the resilient electrical contacts having at least one functional part, formed by a strip of resilient conductive material which, shaped in a section including one or more opposed undulations and terminating in a contact flange for engagement with the tip of the pins, is provided in the positioning or un-plugging position, with a greater length than the distance from the fixed point of anchorage of the contacts in the insulating body member to the tips of the pins in the plugged-in position, in which, consequently, the contacts are compressed.
Further features of the invention are: a) the grounding arrangement is formed by a tab arranged on a surface of the wall of the hollow section of the insulating capsular body member; b) the removable plug member, inside the insulating body member, comprises an power cord including, further to the two current bearing wires, a third ground wire that is connected to a fin of the iron plate member forming the passive armature; and c) the grounding tab of the socket member is of such a length as to make contact with the fin of the iron plate member of the passive armature of the removable plug member before the electrical contacts thereof make contact with the pins of the socket member.
The invention contemplates that the contact flange of the resilient electrical contacts is provided with a contact protuberance conformed by stamping or a contact button made from another good electrically conductive metal.